What to Know About Paxlovid Side Effects Before You Start Treatment

If you've been prescribed Paxlovid 150 Mg /100 Mg Dose Pack (Nirmatrelvir/Ritonavir), you're probably wondering what side effects to expect during your five-day treatment course. The good news is that most people tolerate Paxlovid well. But like any medication, it can cause side effects — and some require medical attention.

This guide covers the common and serious side effects of Paxlovid based on FDA labeling, who may be at higher risk, and when you should call your doctor.

What Is Paxlovid 150 Mg /100 Mg Dose Pack?

Paxlovid is an oral antiviral medication made by Pfizer. It contains two active ingredients: Nirmatrelvir, which blocks the virus from replicating, and Ritonavir, which helps Nirmatrelvir stay active in your body longer. It's prescribed to treat mild-to-moderate COVID-19 in adults at high risk for severe illness.

The 150 Mg /100 Mg Dose Pack is specifically designed for patients with moderate kidney impairment (eGFR 30 to less than 60 mL/min). To learn more about how the medication works, see our guide on what Paxlovid is, its uses, and dosage.

Common Side Effects of Paxlovid

The following side effects are the most frequently reported in clinical trials and post-marketing experience. They are generally mild and temporary:

• Dysgeusia (altered or metallic taste) — This is the most well-known Paxlovid side effect. Many patients describe a bitter, metallic, or "Paxlovid mouth" taste that can last throughout the treatment course. It typically goes away after you finish the medication.
• Diarrhea — Some patients experience loose stools or diarrhea during treatment. This is usually mild and manageable.
• High blood pressure — Elevated blood pressure has been reported. If you already have hypertension, monitor your readings during treatment.
• Muscle aches (myalgia) — Some patients report muscle pain, though it can be difficult to distinguish from COVID-19 symptoms themselves.

These side effects usually don't require stopping the medication. Most resolve on their own within a few days of finishing your 5-day course.

Serious Side Effects of Paxlovid

While rare, some side effects are serious and require immediate medical attention. Contact your doctor or seek emergency care if you experience any of the following:

Severe Allergic Reactions

Signs of a serious allergic reaction include:

• Hives, rash, or skin blistering
• Swelling of the face, lips, tongue, or throat
• Difficulty breathing or swallowing
• Feeling faint or lightheaded

In very rare cases, Paxlovid has been associated with severe skin reactions including toxic epidermal necrolysis and Stevens-Johnson syndrome. These are medical emergencies — go to the emergency room immediately if you develop widespread blistering or peeling skin.

Liver Injury (Hepatotoxicity)

Ritonavir, one of the two active ingredients in Paxlovid, can affect the liver. Watch for:

• Yellowing of the skin or eyes (jaundice)
• Dark-colored urine
• Unusual fatigue
• Loss of appetite
• Abdominal pain, especially in the upper right area

Dangerous Drug Interactions

This is perhaps the most important safety concern with Paxlovid. The Ritonavir component is a powerful enzyme inhibitor that can dramatically increase the levels of other medications in your body. This can lead to life-threatening reactions with certain drugs, including:

• Cholesterol medications like Lovastatin and Simvastatin (risk of muscle breakdown)
• Heart rhythm drugs like Amiodarone and Flecainide (risk of dangerous arrhythmias)
• Sedatives like oral Midazolam and Triazolam (risk of excessive sedation)
• Blood thinners like Rivaroxaban and Apixaban (increased bleeding risk)

For a complete guide, read our article on Paxlovid drug interactions.

HIV-1 Resistance

Ritonavir is also used in HIV treatment. If you have uncontrolled or undiagnosed HIV-1 infection, taking Paxlovid could potentially lead to HIV drug resistance. Inform your doctor if you are HIV-positive or unsure of your HIV status.

Side Effects in Specific Populations

Patients With Kidney Impairment

The 150 Mg /100 Mg Dose Pack is the reduced-dose version specifically for patients with moderate kidney impairment. If your eGFR is between 30 and 60 mL/min, this dose has been adjusted to be safer for your kidneys. Patients with severe kidney impairment (eGFR below 30 mL/min) should not take Paxlovid.

Patients With Liver Problems

If you have moderate liver impairment, your doctor should monitor you more closely. Paxlovid is not recommended for patients with severe hepatic impairment (Child-Pugh Class C).

Older Adults

Older adults, especially those on multiple medications, may be more susceptible to drug interactions. Make sure your doctor reviews all of your medications before starting Paxlovid.

Pregnant or Breastfeeding Women

Data on Paxlovid use during pregnancy and breastfeeding is limited. Discuss the risks and benefits with your healthcare provider. Note that Ritonavir may reduce the effectiveness of certain hormonal contraceptives.

How to Manage Common Side Effects

Here are some practical tips for dealing with the most common Paxlovid side effects:

For the Metallic Taste (Dysgeusia)

• Suck on sugar-free hard candies or mints
• Chew gum between doses
• Drink cold beverages or citrus-flavored water
• Eat strongly flavored foods that may mask the taste
• Remember: the taste goes away after you finish your 5-day course

For Diarrhea

• Stay hydrated — drink plenty of water and electrolyte beverages
• Eat bland foods (toast, rice, bananas, applesauce)
• Avoid greasy, spicy, or dairy-heavy foods
• Over-the-counter anti-diarrheal medications like Loperamide (Imodium) may help, but ask your pharmacist first

For High Blood Pressure

• If you have a home blood pressure monitor, check your readings daily
• Continue taking your regular blood pressure medications as prescribed
• Contact your doctor if readings are consistently elevated

For Muscle Aches

• Rest and gentle stretching can help
• Ask your doctor before taking pain relievers — Acetaminophen (Tylenol) is generally safe, but check with your provider about any interactions

When to Call Your Doctor

Call your doctor if you experience:

• Side effects that are severe or don't improve
• Signs of an allergic reaction (rash, swelling, difficulty breathing)
• Yellowing of skin or eyes
• Unusual bleeding or bruising
• Severe diarrhea that leads to dehydration
• Chest pain or irregular heartbeat
• Any symptom that concerns you

Call 911 or go to the emergency room if you have severe difficulty breathing, widespread skin blistering, signs of anaphylaxis, or chest pain.

Final Thoughts

Most patients who take Paxlovid 150 Mg /100 Mg Dose Pack experience only mild side effects, with the metallic taste being the most common complaint. Serious side effects are rare but important to know about, especially if you take other medications.

The benefits of Paxlovid — reducing the risk of hospitalization and death from COVID-19 — generally outweigh the risks for high-risk patients. Always give your doctor a complete list of your medications before starting treatment, and don't hesitate to call if something doesn't feel right.

If you need help finding Paxlovid in stock near you, visit Medfinder to search local pharmacies.